There are many percutaneous medical devices that function to evacuate air or fluid from body cavities. Conversely, other such devices function to administer a substance, such as a drug, into the body cavity or into a vascular lumen. Most of these percutaneous devices are elongated and tubular, sharing a common method of placement over a guide-wire. This common method is known as the “Seldinger technique.”
The Seldinger technique has revolutionized the practice of medicine by allowing procedures that were previously done with “open” surgical technique to be performed with “closed,” percutaneous technique. As is evident from the following description of the Seldinger technique, the “closed” percutaneous method results in an incision that is just large enough to pass the medical device via a direct tract down to the desired cavity or “lumen.”
To perform the Seldinger technique, a hollow hypodermic needle of the necessary length and rigidity to reach the desired body cavity or lumen is passed through the skin surface until the distal tip of the needle is in the cavity or lumen. The needle is often of a much smaller diameter than the medical device that will subsequently be placed in order to minimize damage in the event the cavity or lumen is initially missed. The position of the distal tip of the needle is then verified by aspirating the appropriate body fluid or air into a syringe. In difficult to access cavities or lumens, radiologic guidance can be utilized to confirm placement. A flexible guide-wire is then passed into the proximal hub of the needle, through the lumen of the needle and into the cavity or lumen. Control is maintained at the distal aspect, or exposed length of the guide-wire. Next, the guide-wire is held in position while the needle is withdrawn over the distal aspect of the guide-wire and removed entirely from the distal end of the guidewire.
The elongated, tubular medical device can be too large and too pliable to easily pass over the guidewire, through the needle hole made in the skin and tissues and into the desired body cavity or lumen. Often, a dermatology, commonly referred to as a “skin nick,” is then performed with a surgical scalpel blade immediately adjacent to the entry of the guide-wire to enlarge to entry site and allow subsequent passage of the medical device.
A well made skin nick should contain the guidewire and should be large enough to admit the medical device. It should not be so large or so deep as to allow leakage of body fluids around the subsequently placed medical device or to excessively compromise the function of the skin as a barrier to infection. If the nick is made away from the entry site of the wire or is not sufficiently deep, the medical device will not pass over the guidewire and through the skin and tissues easily. If excessive force is used the tip of the medical device can flare and bind at the skin surface.
In spite of the fact that a guidewire leads to the precise place where the skin nick is to be made, the dermatology is often performed with only the visual guidance and the free hand of the operator. In urgent settings, with poorly positioned patients, in poorly lighted rooms, a precisely placed skin nick can require significant concentration at a time when there are other pressing issues with the patient.
Devices have been proposed to minimize these safety and procedural difficulties encountered in performing dermatologies in conjunction with percutaneous placements of guide wires. One such device is found in U.S. Pat. No. 5,843,108, issued to Samuels et al. The Samuels et al. device features a central lumen which passed through both the blade and the handle. This device has several perceived weaknesses. The flexibility of the guidewire requires that the operator hold the wire near the proximal, outside end in order to thread the Samuels et al. scalpel over the guidewire. The potential for the operator to sustain an inadvertent laceration is increased by having the operator place their hand in front of the blade. Another disadvantage of the Samuels et al. device is that is utilizes a custom blade that has a central lumen. Such a blade would be relatively expensive to manufacture.
U.S. Pat. No. 4,955,890 to Yamamoto et al. and U.S. Pat. No. 4,633,860 to Korth et al. also disclose surgical devices that aid in percutaneous procedures. However, like Samuels et al., discussed above, both of these devices require the operator to thread the guidewire through a tubular member, very near surgical blades.
A surgical device is needed that minimized the potential for inadvertent lacerations in the performance of dermatologies. Such a surgical device should be disposable, easily sterilized or easily re-bladed. Ideally, the device should be simple and easy to use, without requiring extensive additional training in technique or procedure. The present invention addresses these needs and will be better understood by reference to the following detailed description taken in conjunction with the accompanying drawings.